1. Technical Field
This invention relates to transportation systems and more particularly to personal transit vehicles operating on single rails.
2. Background and Description of Prior Art
Mass transit systems have long been recognized as a desirable means of moving people. Mass transit systems run vehicles at regular intervals capable of moving large groups of people while making predesignated stops. Personal rapid transit (PRT) systems deploy smaller vehicles to move small groups of people with departure and destination based on the demands of the group.
Traditional PRT systems require a proprietary guideway such as a specialized monorail or track. These PRT guideways are distinct from mass transit system railways, expensive to build, and require long term negotiations with private land owners, local, state, and federal governments in order to implement their function. Further distinction from traditional mass transit systems occurs in how PRT vehicles change or turn direction when switching tracks. Traditional trains and light rail vehicles require the track to switch in order for the train to change path. Traditional PRT vehicles have on-board switching devices but require the proprietary guideway to perform such switching. Switching and controlling traditional PRT systems requires a robust communication system that relies on the installation of cable along the guideway or use of the guideway as the communication system. These PRT systems also pass this critical information back to a central computer that makes decisions for each vehicle. In contrast, traditional mass transit trains rely on an operator and trackside signals to communicate. Regardless of communication system, traditional trains as well as PRT's use a predetermined routing or a central computer to navigate along the track or guideway.
Obstructions are handled visually for traditional trains which have an operator to visually confirm that obstructions lie ahead. Traditional PRT systems elevate or submerge the guideway to prevent obstructions from blocking the path and/or use a network of cameras and an operator to inspect the track. Even without obstructions, a stability system is needed. Traditional trains use two rails to remain balanced, while PRT systems use multiple rails or wheels similar to a roller coaster that “clamp” onto the guideway. Additional safety measures are also needed at crossings. A traditional train traverses road crossings based on the types of safety systems installed at the crossing. Where no automated crossing gates exist, the train must proceed slowly in order to avoid vehicles and pedestrians. Where automated crossings exist the train can travel at higher speeds with an improved confidence in safety. Because of the large momentum of a train, a large breaking distance is required to stop and accelerate. Traditional PRT vehicles are generally smaller and lighter than traditional trains, and therefore require shorter breaking distances, but they still require safety gates or visual operator control at crossings.
Mass transit trains make scheduled stops in stations to allow passengers to board or depart. Traditional PRT systems generally stop only at a requested destination. This generally requires side tracks at stations to allow PRT vehicles to stop for boarding without interrupting PRT transit of other PRT vehicles. For boarding and destination selection, mass transit trains use station based kiosks or train attendants to process payment transactions. PRT systems use a similar station based kiosk for payment as well as determining station destination. Protecting stations and vehicles creates a security challenge for train owners. Trains employ a network of video cameras throughout rail yards to track and defray vandalism. For traditional mass transit system, these camera views may be blocked by large trains or require an attendant to monitor the activity.
Multiple prior disclosures, including U.S. Pat. No. 4,089,270 (Sep. 17, 1976) titled “Personal transportation system,” United States Patent Application 20070256588 (Nov. 8, 2007) titled “Monorail vehicle,” and international PCT application WO1999036303 (Jul. 22, 1999) titled “Monorail with bypass and method” disclose vehicles that ride on single rail specific to the disclosed vehicles. U.S. Pat. No. 1,947,119A (Feb. 13, 1934) titled “Monorail car and the like” further discloses a monorail vehicle that stabilizes vehicles on a single rail through a gyroscopic stabilizer or through auxiliary supporting blocks added on both sides of a rail.